Binocular Organization of Visual Cortex in the Cat
By
Izumi Ohzawa

DISSERTATION
Submitted in partial satisfaction of the requirements for the degree of
DOCTOR OF PHILOSOPHY
in Physiological Optics
in the GRADUDATE DIVISION OF THE UNIVERSITY OF CALIFORNIA, BERKELEY

(334 pages: April 4, 1986; Degree conferred: May 20, 1986)


Dissertation Committee:
Ralph D. Freeman, April 3, 1986 (Chairman)
Russell L. DeValois, April 3, 1986
Clifton M. Schor, April 4, 1986

Abstract:

  To determine how neurons in the visual cortex combine input from the two eyes, responses of single neurons are studied quantitatively while sinusoidal grating stimuli are presented dichoptically. The technique allows us to infer functional connections that underlie binocularity of cortical neurons.

  Most simple cells and nearly half of complex cells show large changes in the response when the relative phase of the gratings for the two eyes is varied. It is shown that this type of interaction may be accounted for by linear convergence of input from the two eyes. The results thus provide a unified view of the visual cortex by extending previous knowledge on monocular receptive field properties of cortical neurons.

  A small number of cells, both of simple and complex types, appear monocular when each eye is tested separately, but during binocular stimulation, the silent eye has a clear inhibitory influence which is independent of the relative phase of the gratings. In addition, a type of binocular interaction that is unique to complex cells is identified. Approximately half of complex cells do not show dependence of the response on the relative phase even though they are clearly binocular. In these cells, binocular interaction is apparent only as an increased response during binocular stimulation.

  Effects of monocular and binocular deprivation are studied using the same methods as described above. The data illustrate binocular properties, as revealed by binocular tests, of cortical neurons in these visually deprived animals. This is in contrast to most previous investigations that are primarily concerned with ocular dominance which is determined by monocular tests.

  Finally, a novel visual evoked potential (VEP) is demonstrated. This response may be elicited only with binocular stimulation, and hence it is cyclopean. Unlike those generated by random dot stimuli, the new VEP does not require stereoscopic fusion of the targets.


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Chapters of this dissertation were later published as follows: (Note that the published papers generally reflect additional editing and their contents are not identical to those contained in the dissertation.)

Copyright 1986 Izumi Ohzawa, All Rights Reserved

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